1. Department of Rheumatology and Clinical Immunology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College National Clinical Research Center for Dermatologic and Immunologic Diseases Beijing China
2. Department of Rheumatology, Weihai Municipal Hospital, Cheeloo College of Medicine Shandong University Weihai China
3. Department of Ultrasonography, Peking Union Medical College Hospital Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
4. Department of Rheumatology, Beijing Anzhen Hospital Capital Medical University Beijing China
5. Department of Epidemiology and Bio‐statistics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences & Peking Union Medical College Beijing China
6. Division of Rheumatology, Department of Medicine; and Division of Epidemiology, Department of Biostatistics, Epidemiology, and Informatics University of Pennsylvania Philadelphia